He said that the measures should prevent the government from reaching the $16.4tn "debt ceiling" - the legal limit set by Congress on how much the US government can borrow - for about another two months beyond 31 December.

The measures include:

halting certain financial assistance provided by the federal government to state and local governments

temporarily halting investments in new government debts by state retirement funds for civil servants and postal workers, and by an emergency fund that the government can draw on to defend the value of the dollar

Mr Geithner warned that without them, the government would run out of cash on Monday and "the United States would otherwise default on its legal obligations".

Legislation passed by Congress sets out how much the US government spends on the likes of social security and defence, whilst also legally defining how much the government can raise in taxes.

By imposing a third legal limit - the debt ceiling - the government faces a potentially impossible situation in which it must either disregard the debt ceiling, raise taxes without legal authority, or else default on some of its spending obligations.

The last time that the US government ran up against the debt ceiling, in the summer of 2011, President Obama negotiated a last-minute increase with the Republican-controlled Congress, from $14.3tn to the current $16.4tn limit.

That deal effectively created the phenomenon known as the fiscal cliff - $600bn in automatic tax rises and spending cuts due to come into force on 1 January 2013.

Republicans and Democrats agreed to these draconian measures to slash the government's rate of overspending - its deficit - as a fall-back position, on the assumption that a more sensible agreement on how to cut the deficit would be reached in the meantime.

Mr Obama is expected to meet Republican leaders again to try to negotiate a solution, although no new date has been announced.

Republicans oppose cuts to defence spending as well as the expiration of income tax cuts on the highest earners, which date from George W Bush's presidency.

Democrats want to maintain financial support for lower-income families - including a payroll tax cut and extended unemployment benefits - and oppose cuts to entitlements such as Medicare and social security.

Both sides are keen to avoid taking the blame for the sudden contraction in the government's rate of overspending that would result if no deal is reached.

Failure to do so could damage the US and global markets, and threatens to send the US economy into recession.

Brinkmanship over the 2011 debt ceiling negotiations prompted the rating agency Standard & Poor's to strip the US of its top-ranking AAA credit rating.

The two sides remain far apart, but analysts say a short-term deal may be agreed that will postpone the cuts until spring.

On Wednesday, the Republican House of Representatives Speaker John Boehner called on the Democrat-led Senate to come up with legislation on how it would avoid the cliff, and pass it to the House for consideration.

However, a senior administration official said it was up to Republican leaders not to stand in the way of an agreement.

Despite this, there is little sense of urgency in the capital - the corridors of Congress are silent, the BBC's Zoe Conway in Washington reports.

Changing taxation across the years

Tax year

1993-2000

2001

2002

2003-2008

2009-2012

2012 tax brackets

2013 scenarios

Tax cuts expire

Tax cuts expire for top incomes

Source: Tax Foundation, IRS

Tax brackets shown for unmarried individuals

President

Bill Clinton

George W Bush

Barack Obama

Bottom rate

15%

10%

10%

10%

10%

Up to

$8,700

15%

10%

15%

15%

15%

15%

$8,700-

$35,350

15%

28%

27.5%

27%

25%

25%

$35,350-

$85,650

28%

25%

31%

30.5%

30%

28%

28%

$85,650- $178,650

31%

28%

36%

35.5%

35%

33%

33%

$178,650-$388,350

36%

33% or 36%*

Top rate

39.6%

39.1%

38.6%

35%

35%

Over

$388,350

39.6%

39.6%

*President Obama has previously called for the tax cut to expire for those earning over $250,000

This page is best viewed in an up-to-date web browser with style sheets (CSS) enabled. While you will be able to view the content of this page in your current browser, you will not be able to get the full visual experience. Please consider upgrading your browser software or enabling style sheets (CSS) if you are able to do so.